In U.S. Pat. No. 5,735,278 (Houllt et al) issued Apr. 7, 1998, is disclosed a medical procedure where a magnet is movable relative to a patient and relative to other components of the system. The moving magnet system allows intra-operative MRI imaging to occur more easily in neurosurgery patients, and has additional applications for liver, breast, spine and cardiac surgery patients. The system is used as follows:
The magnet is at first some distance from the operating table, either in the side or back of the surgical room or perhaps within a holding bay area. When imaging is required, the MRI magnet is advanced from its holding area and positioned in the imaging position over the table. Images are taken and magnet is retracted to its holding area.
Thus the MRI system consists of a magnet, rails, installed on the site, and a magnet mover system, which consists of a magnet carriage, cable carrier, and mover control system.
The system is installed in renovated hospital buildings or in new buildings. The system can be installed in one-room or two-room configurations, and may be useable in the future in multi-room configurations. In the two-room configuration, the magnet and MRI system is shared between the two rooms as needed by the hospital staff, leading to increased cost effectiveness within the business case.
For patient and surgical team safety, it is important to have collision detection and anti-collision products attached to the magnet, in order to stop the magnet from moving if collision is detected. Several patents have previously discussed anti-collision methods and technologies for medical devices, with these patents coming from GE, Philips and Hitachi. None of these approaches can be used within MRI systems, because of the magnetic and RF field requirements within the MRI system. None of the previous patents discusses the use of fiber-optics to provide collision detection.